Meles told parliament in a surprise announcement that Uganda and Burundi, the only contributors to the AU force, wanted to withdraw their embattled peacekeepers ahead of Ethiopian troops, who are set to leave next month.

Uganda immediately issued a strong denial that it was withdrawing its troops, while an AU official in Burundi said the country had only Wednesday pledged to send another battalion to Somalia.

“They have already informed us that they would want to withdraw before we do, and we are only waiting for ships and planes to arrive in Somalia in order for them to pull out,” Meles told lawmakers in Addis Ababa.

“At this time, we are looking into every aspect of our withdrawal. The main issue now is to ensure that Ugandan and Burundese peacekeepers pull out safe and sound.”

Uganda’s deputy foreign minister Okello Oryem said he was “surprised” by Meles’ statement. “This is absolutely not true and this is contrary to everything we have said. Our position has always been that if Ethiopia pulls out of Somalia, we will increase our presence there,” Oryem told AFP.

“Uganda is prepared to increase its battalion if there is a need,” he added.

Neither country had given any hint that it wanted to withdraw its troops from the beleaguered AMISOM force, which numbers some 3,400. Withdrawal would leave Somalia’s weak transitional government at the mercy of a resurgent Islamic rebellion.

Ethiopia announced last month it was ending its two-year intervention in Somalia, where it sent some 3,000 troops in 2006 to prop up the government and clear the threat of an Islamic insurgency from its own borders.

That announcement caused panic within the African Union, whose under-equipped peacekeepers are meant to take over security duties but need more time to prepare, and get up to full operational strength of 8,000.

Addis Ababa subsequently said it was prepared to delay its pullout “by a few days” in order not to expose AU forces to an onslaught by the Shebab, the Islamist insurgents who control large parts of Somalia and have been closing in on Mogadishu in recent weeks.

A senior AU official told AFP after Meles’ statement that “we know that the Amisom soldiers have been worried since the announcement of the Ethiopian withdrawal.

“Our policy is to try to reinforce AMISOM, and to convince the contingents already there to remain. We haven’t yet been officially informed about this wish to withdraw by the two countries,” said the official on condition of anonymity.

The AU has meanwhile been scrambling to avoid a “security vacuum” in Somalia, and on Wednesday its chief Jean Ping called on the UN Security Council to authorise the deployment of UN forces in Somalia.

At least nine AU peacekeepers have been killed in Somalia since they were first deployed in March 2007.

Meles said in his speech to parliament on Thursday that “our decision will never be reversed no matter what the international community says or does.

“Even if they (the peacekeepers) change their mind and stay, or even if the international community fails to provide the necessary transport service, we will do whatever means necessary to pull out without postponing.

“Similarly, the AU has also informed us that it would want its troops out before our withdrawal if we were ever going to implement our decision. The AU asked for security and support in order to ensure the safe passage of the Ugandan and Burundese troops.”

The insurgent Shebab, the former youth and military wing of the Islamic Courts Union, has waged a bruising guerrilla war in the country, which has been without a functioning government since 1991.